Known windshield wipers have a wiper arm comprising a mounting part and a joint part having a wiper bar hinge-mounted on this by way of a hinged arm. The mounting part sits on a drive shaft that is supported in a bearing housing and swivels the wiper arm basically parallel to a vehicle windshield. A wiper blade is hinge-mounted on an open end of the wiper bar. The wiper blade has a usually multisectional carrier strap system having secondary straps hinge-mounted on a middle strap, of which at least a few hold a wiper strip on its headpiece by way of claws on their ends. The multisectional carrier strap system and springs inserted in the headpiece make it possible for the wiper strip to adapt to a curved vehicle windshield with an even bearing pressure during wiping. A tension spring preloads the hinged arm for this purpose. Such windshield wipers are made known in DE 37 44 237 A1, for instance. In simplified embodiments, secondary straps-also called intermediate straps and claw straps-can be eliminated. In the simplest case, the middle strap itself has claws, with which it holds the wiper strip.
A wiper device for windshields of motor vehicles is made known in DE-AS 16 80 194, in which a wiper arm lies in a park position when swiveled in by way of a lifting device which is formed by a plunger acted upon by a spring and which lifts the wiper arm having the wiper blade away from the vehicle windshield when it extends. The plunger is retracted and the wiper blade is placed against the vehicle windshield once more in that a controllable solenoid is activated. If the plunger actuation fails, the plunger would remain in the extended position. In this position it lies in the range of motion of the wiper arm, however, which can result in damage to the windshield wiper.
A windshield wiper for motor vehicle windshields is made known in DE 42 02 965 C1, the wiper arm of which lifts in a park position by way of a lifting device and the wiper blade thereby lifts away from the vehicle windshield. The lifting device includes a lifting arm that is supported outside of the area traversed by the wiper arm and the wiper blade and that has a lifting height in its working position which-based on an area covered by the wiper arm-corresponds to a position of the lifting arm that overlaps the windshield wiper in its wiping position with free travel. This prevents a situation in which, if the lifting device is defective, the motion of the wiper arm collides with the lifting arm and the wiper device is damaged.
A wiper system for motor vehicle windshields is made known in DE 32 28 087 A1 in which the contact pressure of the wiper arm can be adjusted by the axial stroke of a plunger. The plunger acts on a double-armed lever that is situated along the wiper arm longitudinal direction. As a result, pressure on the wiper blade in the park position of the windshield wiper is released, and the wiper lip is protected from permanent-deformation.
Moreover, a windshield wiper for motor vehicles is made known in DE 40 28 494A1 in which the contact pressure of the wiper arm is reduced when the motion is reversed, in order to prevent noises. To this end, a rocker arm is supported on a joint bolt of the hinged arm that carries a hinging device for the tension spring on one end of a lever arm and includes a roller on the end of the other lever arm that runs on a ramp provided next to the bearing housing. The hinging device is displaced by way of the ramp and the rocker arm as a function of the rotary position of the wiper arm in such a manner that the contact pressure of the wiper arm in the reversing positions of the windshield wiper is reduced.
According to the invention, the rocker arm is supported in a swing bearing on the mounting part, and a ramp attached to the motor vehicle controls the cooperating end of the rocker arm. As a result, it is ensured by way of simple and reliable means that the wiper blade in the park position is lifted away from the vehicle windshield. Pressure on the wiper lip of the wiper blade is released completely when the windshield wiper is shut off, so it does not become permanently deformed over a long period of time, which would impair the wiping quality. Moreover, it prevents a situation in which the wiper lip freezes to the vehicle windshield when frost forms and is damaged when pulled loose.
The ramp itself is a simple component that is advantageously an integral component of the cleaning system and is preferably attached to the bearing housing of the windshield wiper.
The rocker arm can be supported in its own swing bearing on the mounting part. In a simple manner, however, it is advantageously supported on an arm axis of the hinged arm. In order to reduce the friction between the ramp and the rocker arm, a roller is provided on the end of the rocker arm that cooperates with the ramp.
Since the wiper arm does not necessarily have to be lifted away from the vehicle windshield every time when it reaches the park position, but rather only when the windshield wiper is turned off, the solution is especially advantageous for wiper systems having an extended park position that is entered into only when the windshield wiper is turned off. In this case, the ramp is adjusted to the wiper system in such a way that the rocker arm lifts the joint part having the wiper blade away from the vehicle windshield in the extended wiping angle range of the parking position.
The wiper blade is usually located in the park position in a so-called hood gap between the engine hood and a windshield of the motor vehicle. Since the width of the hood gap is different on different types of motor vehicles, it is appropriate that the lifting height of the wiper blade from the vehicle windshield is adjustable. This can take place, for example, in that the angle of the rocker arm, which includes its ends, is adjustable, e.g., by way of bending or adapters that are placed on the ends of the rocker arm.